Greenhouse and tunnel films are generally made at very high layflats, as high as 65 feet. As a result, bubble stability is very important during production. Greenhouse and tunnel films must:
- Resist exposure to UV
- Resist fogging due to condensation of interior moisture
- Resist environmental contaminants (acid rain, particulate)
- Be tough enough to withstand abuse
- Allow the transmission of light
UV protection and antifogging are typically accomplished using additives. A typical film might be made of a blend of LLDPE and LDPE, with additives. A low MI LDPE (0.2) provides the best stability, but the least favorable clarity. Adding a high MI LDPE (2.0) will give better clarity, but less bubble stability. The choice of LLDPE and LDPE also depends on equipment capabilities.